Prevalence and Diversity of Fusarium Species in Oat Grains Harvested From Commercial Oat Fields in Ireland in 2022

This study investigated the prevalence and diversity of Fusarium species infecting Irish winter and spring oat ( Avena sativa ) fields during the 2022 growing season, aiming to assess implications for mycotoxin contamination and crop management strategies. A total of 4140 fungal isolates were obtained from surface‐sterilised oat grains collected at growth stage (GS) 92, derived from 44 oat fields sampled from across the south‐east of Ireland. Fungal isolates were characterised based on their colony morphology and spore characteristics on quarter‐strength potato dextrose agar (PDA) and grouped into 16 distinct morphological groups. Over 700 samples representing all fungal isolates obtained from nine field locations in Ireland had their rDNA internal transcribed spacer (ITS) region sequenced to identify which morphological groups contained Fusarium spp. All fungal isolates from all field locations in Ireland identified based on morphological characteristics and ITS sequencing as belonging to the Fusarium genus were further intraspecifically identified based on sequences of the translation elongation factor 1‐α ( TEF1‐α ). TEF1‐α sequence analysis of all Fusarium isolates confirmed that Fusarium langsethiae was the most prevalent species, detected in 94% of the fields sampled. However, despite the high prevalence of F . langsethiae across different field locations, its incidence was low, accounting for less than 6% of the total fungal isolates obtained. Other Fusarium species detected included F. tricinctum , F . poae , F. avenaceum and F. culmorum . The widespread prevalence of mycotoxic fusaria highlights the need for comprehensive monitoring and integrated management strategies to mitigate mycotoxin risks and ensure the safety and quality of oat products.